North Carolina building code requires two HVAC returns for homes over 1,600 sq ft to improve airflow and prevent the system from pulling unconditioned air from crawl spaces. A properly sized air-conditioning unit already dehumidifies your home; a separate dehumidifier is only needed in a sealed crawl space. Oversized units short-cycle and fail to dehumidify properly.
Questions this video answers
North Carolina code changed in 2008‑09 to require two returns for homes over 1,600 sq ft. Multiple returns improve airflow, reduce the system’s workload, and prevent the unit from pulling unconditioned air from crawl spaces or the attic.
Your air‑conditioning system already dehumidifies when properly sized. A separate dehumidifier is only needed in a sealed crawl space. Oversized units can fail to dehumidify, leading to a cold‑clammy feel.
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Hey, on this episode, why do I need two returns in my house, and do I also need a dehumidifier? You ask your comfort and energy questions and they get answered. This is the Ask Derrick Cole Show. Hey, this is Derrick Cole with episode 82 of the Ask Derrick Cole Show, answering your home and energy questions. And today we have a question from the woman behind the camera because she had a few days off. One of us was on vacation last week. We couldn't film the show. She was moving into her new house, and she has this question.
I moved into my almost 1,700 square feet home and have 2 returns. My other house had 1 return. Why do I have 2?
In 2008 or '09, they changed the code in North Carolina. Anything over 1,600 square feet, you have to have 2 returns in the home instead of 1 return. The house is big enough, and I would always recommend having multiple returns because I've— out of 15 years, I've never been to the home and been like, wow, we have too many returns here. That's never been the case. What has been the case most of the time is you go to a house and you say, "There's not enough return here. Stop shutting that door. You don't have return. The return is way over on this side of the house." So with 2 returns in this 1,700-square-foot house, we'll say, you have probably have 1 return on 1 side and 1 return on the other side. So probably how it's laid out is that you have a room or bedrooms on this side with the return. You have the kitchen, living room in the middle, and on this side you have rooms rooms and a bedroom with another return. See, I haven't even seen the house. So that's why you have 2 returns. You want to make it as easy as possible for the air to get back to the unit. So the bigger the return and the more you have in these different locations where it can be closed off, the better, because you want to make it very easy. Otherwise, the unit's going to get the air it needs. It's going to suck it through the crawl space to the attic, to the outside. It's going to get the air. It wants to get to operate, but you want to control it. You want it to be cool or warm filtered air from your return, not from the outside, which is unconditioned air, right? So that'll save you energy and the unit will not have to work as hard to get the air back to it. So that is why you have two returns. Two returns is not a bad thing. I'm glad you have two returns because you need two returns because If you have that one return on this side of the house and you have this other 1,600 square feet, all that air has to get back to this side of the house one way or another. And we all know it's gonna be very difficult on that back room when you shut the door because that's your junk room. You have all your stuff in there. You don't want people to see it. It's gonna be very hard for the air that's coming out to then get back to the return. Is it— is there a jungle room?
Do I need a dehumidifier in my house?
Everybody needs a dehumidifier in their homes. I'm not being sarcastic, but it's called your air conditioner. That is a dehumidifier. That's what makes you feel comfortable when it's nice and muggy and hot outside. You feel nice and cool inside because You're removing the heat from the home, but it's also dehumidifying at the same time. So what we run into a lot in this area is you do need dehumidifier in the crawl space if it's sealed. Now, if it's not sealed, you don't need a dehumidifier because then you're dehumidifying the whole world, which is not really going to work out in your favor. You're just going to run, run, run, run. But if your home is properly insulated, properly sized unit in your house, then your AC should reach that set point and should keep you comfortable. It's something you notice, and the reason we're getting this question, something you notice a lot more in the summertime when it's hot and muggy versus the wintertime when it's, you know, humidity is kind of like a blanket. Humidity keeps you nice and toasty. So in the wintertime, Obviously, we don't have many complaints about, you know, "It's a little humid in here." No, you don't hear that call, but you do hear it in the summertime. So you need to make sure your unit is sized properly for the home. I've gotten quite a few questions of, "You know what, I like to keep my home at 68. Can I just put a 5-ton unit in and be done with it?" No, because for one reason, you have a 3-ton system. And you have a 3-ton duct system. So you put a 5-ton unit on a 3-ton duct system, you still have a 3-ton duct system. So it makes no sense to do that. Plus, if the unit is too big for the home, it's not going to probably dehumidify. Yes, it's going to hit that temperature set point in the home, but you're not going to be comfortable because it's going to come on and off, on and off. You've been to those bigger commercial buildings or courthouses where it feels kind of cold and clammy. It's kind of— it's because it's not dehumidifying. That's why you're getting that feeling. So you don't want that feeling inside your house. So yes, use your dehumidifier, your air conditioner in your home, but it needs to be properly sized so you're comfortable. All right, that's episode 82 of the Ask Derrick Coles Show. Be sure to hashtag your questions. Ask Derek Cole, and we'll get him on the show.
